Barn Spiders in Wisconsin - Identification, Behavior and Pest Control Benefits

Barn Spiders in Wisconsin - Identification, Behavior and Facts

Wisconsin is home to a variety of spider species, including several types of barn spiders. Barn spiders are medium to large spiders that build their webs in man-made structures like barns, sheds, and houses. Some of the most common barn spiders found in Wisconsin include the banded garden spider, marbled orb weaver, and common house spider.

Barn spiders play an important role in controlling insect pests while also being harmless to humans. By learning to identify these spiders, Wisconsin residents can appreciate them and coexist peacefully.

Identifying Barn Spiders in Wisconsin

Here are some of the most common barn spiders found around Wisconsin homes and properties:

Banded Garden Spider

The banded garden spider (Argiope trifasciata) is a large orb weaver spider with distinctive markings. The abdomen has yellow and black bands with silver flecks, along with black and yellow striped legs. Their orb webs can reach up to 2 feet across.

These spiders are most active during the summer and early fall when they build their large, stunning webs in gardens, fields, and around barns. The webs have distinctive zig-zag patterns through the center.

Marbled Orb Weaver

The marbled orb weaver (Araneus marmoreus) is another type of orb weaver known for the colorful patterns on its rounded abdomen. The abdomen has a mix of grey, black, yellow, and orange with speckling and marbling.

This medium-sized spider builds orb webs up to 2 feet across on porches, in trees, and around outbuildings. Their webs are decorated with zig-zag patterns and have a hole in the center where the spider waits for prey.

Common House Spider

As their name suggests, the common house spider (Parasteatoda tepidariorum) frequently lives around and inside human homes. They build tangled, messy webs in garages, crawl spaces, window corners, and other sheltered spots.

These spiders have variable coloration but most appear greyish-brown. The oval abdomen often has faint chevron markings. They have a legspan around 1/2 inch wide when fully grown.

Web-Building Strategies

Many barn spiders have special web-building strategies to capture prey while also protecting themselves:

• Orb weavers carefully construct symmetrical orb webs with support strands, spokes, and sticky spirals. The holes in the center allow the spider to retreat from predators.
• Funnel weavers spin dense, funnel-shaped webs that lead flying insects into the narrow end where the spider waits unseen.
• Cobweb spiders build messy, tangled webs that rely on trapping insects that fly or crawl into the strands.

Web designs take advantage of airflow patterns, visibility, and locations where insects are likely to pass through. Spiders often eat and rebuild their webs daily.

Prey Capture and Feeding

Once prey enters the web, the waiting spider rushes out to bite and wrap it in silk. Barn spiders employ a variety of strategies to subdue and consume their prey:

• Orb weavers like the banded garden spider wrap prey thoroughly to prevent escape.
• Cobweb spiders like the common house spider pounce quickly and bite prey held in their fangs.
• Funnel weavers grab victims through the narrow end of the funnel before biting.

Spiders use venom and digestive enzymes dissolved in liquid to break down the preys insides. They then suck out the nutritional liquefied remains.

Spider Reproduction

Late summer through fall is mating season for many barn spiders. While courtship rituals vary, male spiders deposit sperm into the females reproductive organs in most cases. The females lay eggs shortly after and wrap them in a protective silk sac.

Spiderlings hatch in spring or early summer and molt frequently as they mature over summer and fall. Most barn spider species live for one year.

Barn Spider Bites

Barn spiders very rarely bite humans, but it can happen if they feel threatened or get pressed up against bare skin. Symptoms are usually mild pain, redness, and swelling at the bite site.

Spider bites can be avoided by taking some simple precautions:

• Wear gloves when cleaning garages and sheds
• Shake out clothes, towels, and bedding before use if they've been in storage
• Don't put bare hands in areas you can't see clearly

See a doctor if you experience severe reactions, swelling, or think an infection has started.

Benefits of Barn Spiders

Barn spiders provide free pest control by eating flies, mosquitoes, moths, crickets, and other arthropods around Wisconsin homes and farms. Their webs also capture many disease-carrying insects.

By leaving these harmless spiders alone, homeowners can take advantage of their voracious appetites that keep pest numbers in check. Spider webs in barns and sheds are signs of a healthy ecosystem.

Coexisting Peacefully With Barn Spiders

While spider phobia affects some people, most barn spiders in Wisconsin are not dangerous. Here are some tips for calmly coexisting:

• Learn to identify spider species to understand which ones are harmless.
• Avoid touching or disturbing webs.
• Use brooms or hoses to remove webs if they are in an inconvenient spot.
• Remove clutter to discourage spiders from building nests and webs.
• Install screens on windows and doors to prevent spiders entering living areas.
• Turn off exterior lights at night to avoid attracting insects that spiders prey on.

With a little care and understanding, Wisconsinites can enjoy the benefits of barn spiders safely and peacefully.

Frequently Asked Questions About Barn Spiders in Wisconsin

What is the biggest spider found in Wisconsin?

The largest spider commonly encountered in Wisconsin is the black and yellow garden spider, which has a legspan up to 2.5 inches. Wolf spiders and fishing spiders can also reach impressive sizes up to 2 inches across.

How big do barn spiders get?

Most barn spiders in Wisconsin have legspans between 0.5 - 2 inches when fully grown. The marbled orb weaver is among the largest at just over 2 inches legspan. Funnel weavers and common house spiders have legspans around 0.5 inches.

Are barn spiders poisonous to humans?

No, the types of spiders found around barns in Wisconsin are not considered dangerous to humans. Barn spiders have venom to subdue their prey, but their bites cause only mild irritation in most cases. There are no spiders in Wisconsin with venom capable of causing serious harm to people.

What is the lifespan of a barn spider?

Most barn spiders in Wisconsin live for approximately one year. After hatching in spring or early summer, they will grow to maturity by late summer/early fall, mate, lay eggs, and die in the fall or winter after their first and only breeding season.

Should I kill barn spiders?

There is no need to kill barn spiders in most cases. They provide free pest control services by eating insects, and their populations naturally fluctuate without growing out of control. As long as webs are not causing major problems, the spiders can be left alone or gently moved.

What eats barn spiders?

Barn spiders fall prey to a wide array of generalist predators. Birds, rodents, wasps, beetles, and other spiders all eat barn spiders. Their eggs can be eaten by insects like ants. However, barn spiders produce many offspring to account for losses.

How do barn spiders catch prey?

Different barn spiders have evolved varied techniques for catching food. Orb weaver spiders use sticky spiral webs to trap flying insects. Funnel weavers hide and strike from funnel-shaped webs. Cobweb spiders run down prey ensnared in messy webs. All inject venom to paralyze and liquefy prey.

Do male barn spiders get eaten?

Female barn spiders do sometimes eat the male after mating. However, males have strategies to avoid being eaten. For example, they quickly flee the web after mating. Males also release sperm on the web rather than directly to the female during courtship.

Where do barn spiders lay their eggs?

Female barn spiders produce an egg sac made of thick silk that houses 100-1000 eggs. The egg sac is attached securely to a web or hidden in a protected nook. The female guards the egg case aggressively until hatching.

Do barn spiders come inside houses?

Some types like the common house spider routinely live inside as well as around human structures. Other barn spiders only wander inside accidentally while hunting prey. They may be carried inside on objects like firewood. Keeping screens in good repair can prevent indoor infestations.

Are barn spiders attracted to light?

Most barn spiders remain near their webs to catch passing prey rather than moving toward light sources. However, the insects they eat are drawn to lights, in turn attracting the spiders. Reducing outdoor lighting can minimize this effect.

What times of year are barn spiders most active in Wisconsin?

Late spring through early fall is peak activity season for barn spiders in Wisconsin. They are most abundant in late summer and early fall when prey is plentiful. Activity tapers off in fall as temperatures drop and spiders reach the end of their 1-year lifespans.

What species of barn spiders live in Wisconsin?

Some of the most common barn spider species found in Wisconsin include: banded garden spider, marbled orb weaver, barn funnel weaver, common house spider, cobweb spiders, ghost spider, dwarf hammock spider and others.

Conclusion

Barn spiders are ubiquitous around rural Wisconsin homes and properties, where they serve as free insect pest control. While startling if encountered unexpectedly, they pose little risk to humans and should be left alone to play their important ecological roles. With proper identification and care, barn spiders and Wisconsin residents can coexist peacefully.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.